Dr. Jay Luthar and Dr. Julia Loewenthal, physicians at Lutanen Health in Boston's Back Bay, have been named 2026 Castle Connolly Top Doctors, marking their second year receiving this distinction. Only 7 percent of the nation's licensed physicians are selected annually as Castle Connolly Top Doctors for their specialties in their regions, according to Castle Connolly.
Lutanen Health is a bespoke primary care and longevity practice grounded in the belief that deep, sustained relationships and strategic health stewardship are foundational to effective medicine. Unlike traditional volume-driven practices, each physician at Lutanen Health cares for no more than 150 patients, enabling personalized attention. The practice is the only academically affiliated primary care practice in Boston that integrates longevity science into everyday care.
"The Castle Connolly recognition affirms what I believe matters most in medicine: time, trust, and partnership," said Dr. Luthar. "Dr. Loewenthal and I share the conviction that care should be uniquely designed for each individual patient. When you understand someone's biology, context, and goals over time, you can offer care that is not only more effective but deeply human."
At Lutanen Health, primary care becomes private health management, identifying risks long before symptoms emerge and allocating interventions across a lifespan to preserve vigor and delay decline. Drs. Luthar and Loewenthal are fellowship trained in integrative medicine, bringing mind-body science and holistic approaches to lifestyle optimization. Their newly designed 3,000-square-foot healing space in Back Bay includes a state-of-the-art human performance laboratory.
The practice evaluates and treats a wide range of primary conditions, focusing on metabolic health, cardiovascular risk reduction, cognitive preservation, and healthy aging. The clinical team specializes in managing complex internal medicine cases while addressing unique needs of older patients, including frailty risk, medication optimization, and age-related vitality. Advanced diagnostic technologies include AI-guided plaque detection, multi-cancer early detection blood testing, VO₂ max testing, biological age tracking, advanced biomarker and genetic analysis, comprehensive fitness and mobility assessment, and structured sleep evaluation.
Practice amenities reflect its relationship-driven model: extended visits, same-day appointments, 24/7 physician access, individualized nutrition counseling, and for select patients, home visits to ensure continuity and high-level integrative care. Complimentary valet parking is also available.
Dr. Luthar completed his medical residency at Cambridge Hospital, a Harvard Internal Medicine Residency Site, and is board-certified in Internal Medicine, Integrative Medicine, and Lifestyle Medicine. Dr. Loewenthal completed her Internal Medicine residency at Brigham and Women's Hospital and her fellowship in Geriatric Medicine through the Harvard Multi-Campus Geriatrics Program. She is board-certified in Internal Medicine and Geriatric Medicine and board eligible in Integrative Medicine. Both physicians maintain academic faculty roles at Harvard Medical School, where Dr. Luthar serves as an Instructor and Dr. Loewenthal serves as an Assistant Professor.
Top Doctors are nominated by peer physicians and selected by the physician-led Castle Connolly research team. Castle Connolly publishes its Top Doctors list at castleconnolly.com and in various print and online partner publications. Nominations are open to all board-certified MDs, DOs, and DPMs. Honorees are chosen based on criteria including medical education, training, hospital appointments, and disciplinary histories. Doctors do not and cannot pay to be selected as a Castle Connolly Top Doctor.
